The protective functions of grounding.
The main function of grounding is to divert currents from where they can pose a hazard to humans. For example, if the underfloor heating in a bathroom with high humidity is not earthed, if the supply cable is damaged in any way, a person may feel an electric shock when touching a metal pipe or the casing of a washing machine. Grounding will carry the dangerous potential into the ground, thus safeguarding you from electric shock. In this regard, the arrangement of quality grounding is a must when installing electric floor heating.
Connecting an electric heat field to the power supply is not difficult. This is due to the fact that virtually all modern systems use grounding sheath (conductor) cables. So you only need to make connections in strict accordance with the markings:
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A building with many apartments
If it is not a modern construction, it is more likely that a TN-C type earthing system was used in the construction of the house. This type provides the grouping of neutral and ground wire throughout the circuit.
Notwithstanding the fact that this arrangement provides protection against electric shock, injury can still occur. This occurs when the neutral wire is broken, based on this, immediately triggered phase voltage.
The greatest degree of protection can be provided by the TN-S discharge system, widely used in today’s construction. The scheme provides for the division of zero and ground throughout the electrical chain. What’s more, the fact that the latter penetrates the ground at the transformer station adds extra safety.
When the heating component is equipped with a metal sheath, it must be connected to a PE bus. This is done by connecting to the actual socket equipped or specifically on the switchboard itself.
If the heating element has no protective shielding, it is better to lay a metal mesh on top of the heated floor surface, which is then attached to a suitable busbar.
Under practical conditions the TN-C system is popular, in other words it is realized with the help of 2 wires: phase (L) and work with a combination of zero (PEN).
Thanks to this, when arranging under-floor heating, earthing should be arranged on an independent circuit. It consists of horizontal and vertical earthing switches hammered into the ground.
If grounding is prepared through the body of the switchboard, in this case it is recommended to install a ground fault interrupter, as an additional means of electrical protection.
To be installed specifically in the distribution board. Connect a specialized wire from the body of the electric element to the grounding busbar. As mentioned before, in the absence of a protective shell, a metal mesh is installed, which must be plugged into the overall system and, based on this, connected to the bus.
Occasionally there are situations in which, despite the established earthing, there are still leakages of alternating current. Then in a very short time it is necessary to determine the point of failure using specialized instruments for measurements and completely localize it. For a real beautification of effectively functioning earthing there are on sale ready-made kits that include everything you need for installation.
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Whether or not to ground the underfloor heating?
In the arrangement of the floor heating, many people give preference to electric systems. But, like any other device operating from a socket, such a floor must be equipped with a very important functional element. it is the grounding of the floor heating.
Cable or film heating system is capable of quickly, efficiently and evenly heat not only the floor but also the surrounding objects. But in order to take full advantage of all these benefits, the system should be properly arranged so that it not only functions correctly, but also does not pose a threat.
Therefore, it is not necessary to practically check whether the floor heating can electrocute, it is advisable initially when installing the heating system to provide high-quality grounding, without thinking about whether it is necessary.
If you do not do this, for example, in the bathroom, which differs from other rooms with high humidity, then in case of emergency damage to the film or cable, you can easily feel the electric shock by touching a metal part, the body of the washing machine or just a pipe.
With an earthing switch the dangerous portion of the electric current can escape unhindered through the ground thus protecting the occupants from electric trauma. Due to the fact that many manufacturers of electric underfloor heating are using a cable with a ground wire as a heating element, it only remains to make a competent connection strictly to the marking correspondence (N-zero, L-phase and PE-ground wire).
Do I need a grounding for the electric floor??
Nowadays, innovative products that can make life and living of modern people more convenient and comfortable are very popular. One such innovation in today’s homes is underfloor heating. This system of floor heating is widespread, and almost no repair can do without it. Many apartment owners who performed the repair work yourself, often faced with the fact that after installing the floor, there was an unpleasant tingling sensation as a result of touching metal objects. What causes electric shocks and how to protect yourself from its effects?
Electrocution, in conditions of a heating system. Underfloor heating, occurs as a result of touching live parts of the system or current leakage through the insulation breakdown. That is, such exposure occurs if no system of protection against electric shock or this system has failed. What to do?
First, if there is no protection system, it must be installed. Electric floor, like any other system with an electrical installation, requires the use of protective disconnection device RCD with a tripping current of up to 30mA, in direct contact with live parts of the installation, as well as protective earthing, in case of damaged insulation.
The RCD is installed in the switchboard;
For grounding, it is sufficient to connect a special wire from the body of the electrical element to the grounding bus in the switchboard, since all modern electric floor heating elements have a protective metal shell. If this is not available, then a metal mesh is installed on top of the heater, combined into a single system, and connected to the grounding bus;
If the floor heating is installed in a private home, we recommend that you make a separate earthing connection, for example with the ZZ-6 set.
Secondly, if a protection system is already installed, but a sudden electrical leakage occurs, it is necessary to localize the fault point by calculating it using special measuring instruments.
We should add that, no matter what kind of floors are in the house, you must apply the equipotential bonding when using electrical appliances.
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Do you need a RCD for underfloor heating??
Do you need a separate RCD for the floor heating? This question is asked by many buyers of electric floor heating. So, if you plan to install underfloor heating systems in rooms with wet kitchen, bathroom, then you definitely need.
Ground fault interrupter (RCD) must be installed to protect people from electrical leakage. For correct work RCD screen of heating cable grounding (connect to PE protective conductor) or if the network two-wire, you must do protective grounding. That is, the screen connect to zero before the RCD.
RCD will protect you in case of a violation of the insulation of the floor heating, the integrity of the connection or the final sleeve. Such options are especially common if the floor heating was not installed by a specialist.
RCD will disconnect the load (floor heating) in case of leakage current to ground.
How to connect the floor heating with a RCD
In addition, for load circuit protection against short circuit it is necessary to install a circuit breaker in the phase wire gap of the power circuit of the thermal controller. Designed for a current not exceeding 16A.
Wiring diagram RCD on the electric floor heating
However, in the extreme case, if you already have one RCD installed for the whole apartment, designed for a leakage current of 30 mA, you can not install additional RCDs for the floor heating. If this is not the case and is not planned, you must install a RCD for the floor heating, rated at 10 mA leakage current (for the bathroom) and 30 mA for the other rooms.
Instead of RCD you can put a DIFFASMAT, and what to choose from them you can learn after reading the article Uzo or DIFAVT
Do not neglect your safety and the safety of your family be sure to connect the floor heating through RCD.
If you still have doubts, you can read reviews on the forum.
Connecting a floor heating system without grounding
When it comes to underfloor heating, many people prefer electric systems. But, like any other device operating from the socket, such a floor must be equipped with a very important functional element. it is the grounding of the floor heating.
Cable or film heating system is able to quickly, efficiently and evenly heat not only the floor itself, but also the surrounding objects. But in order to take full advantage of all these benefits, you should properly equip the system so that it not only functions properly, but also does not pose a risk.
SlimFix low profile underfloor heating installation by Continal Underfloor
Therefore, you should not practically check whether the floor heating can electrocute, it is advisable initially when installing the heating system to provide high-quality grounding, without thinking about whether it is obligatory.
If you do not do this, for example, in the bathroom, which is different from other rooms with high humidity, then in case of emergency damage to the film or cable, you can easily feel the electric shock by touching a metal part, the body of the washing machine or just a pipe.
In the presence of the grounding device dangerous portion of the electric current will go through the ground unhindered, thereby keeping people in the building safe from electrical injury. Since many manufacturers of electric underfloor heating systems use a cable with a ground conductor as the heating element, all that’s left to do is to make an accurate connection in strict accordance with the marking (N-zero, L-phase and PE-grounding wire).
If it is not a modern construction, it is more likely that a TN-C type grounding system was used when the house was built. This type implies the connection of the neutral conductor and the ground conductor throughout the entire electrical circuit.
Even though this arrangement provides protection against electric shock, injury can still occur. This occurs when the neutral conductor is broken, so the phase voltage is immediately triggered.
The TN-S system of discharge, widely used in modern construction, can ensure the highest degree of protection. The scheme involves the separation of neutral and ground throughout the electrical chain. In addition, additional safety is added by the fact that the latter penetrates into the ground in the area of the transformer substation.
When the heating element is equipped with a metal sheath, it must be connected to the PE bus. This is done by connecting to a specially equipped socket or directly to the switchboard itself.
If the design of the heating element has no protective sheathing, it is advisable to put a metal mesh over the surface of the warm floor, which will subsequently be fixed to the appropriate busbar.
In practice, the TN-C system is demanded, i.e. it is realized with two wires: phase (L) and operating with combined neutral (PEN).
That’s why the installation of electric underfloor heating requires the installation of grounding with an independent circuit. It is a vertical and horizontal earth electrodes driven into the ground.
If grounding is arranged through the body of the switchboard in that case it is recommended to install RCD, as an additional means of electric protection.
The device of protective switching-off
Mounted directly in the switchboard. Connection of a special wire from the body of the electric element to the grounding busbar. As mentioned earlier, in the absence of protective sheathing, a grid of metal is mounted, which must be plugged into the general system and, accordingly, connected to the bus.
Sometimes there are situations where, despite the installed earthing, electrical current leakage still occurs. Then as soon as possible it is necessary to calculate the failure point using special measuring instruments and fully localize it. For a complete and efficiently functioning earthing installation, ready-made kits are available which include everything you need for installation.
Install and connect the thermostat
The thermostat is usually plugged into the wall like a normal switch. Choose a place for it near the existing electrical wiring, such as near a socket. First of all, an opening is made in the wall, the thermostat junction box is installed there, and the leads (phase and zero) of the mains and the temperature sensor are led to it. The next step is to connect the thermostat.
On the side of the thermostat are “sockets”. Here the cables for the mains (220V), the sensor and the heating cable are led.
It is helpful to know that the wires that are connected when installing the thermostat are color-coded:
Connection of the floor heating to electricity is performed in the following order:
- On pins 1 and 2, the 220 V lines are connected. The polarity is to be strictly observed: The wire L (phase) is led to pin 1, the wire N (zero) is led to pin 2.
- On pins 3 and 4 led the heating cable of the floor heating, according to the principle: pin 3. wire N (zero), pin 4. wire L (phase).
- The wires of the temperature sensor (usually embedded in the floor, i.e. determining the temperature in the floor thickness) are connected to “sockets” 6 and 7. The principles of polarity need not be observed here.
- Check if the thermostat works correctly. To do this, turn on the power.220V, set the minimum temperature on the device and turn on the heating elements (by turning a knob or pressing a button). After that change the heating mode to maximum, ie “program” the thermostat to the highest temperature possible for it. The correct operation of the device will announce itself with a click, which will indicate the closure of the circuit heating.
Wiring Diagrams may vary slightly, depending on the types and models of thermostats. Therefore, in order to prevent the user from making a mistake, on the body of the device, as a rule, prescribe all the contacts.
Slight differences in connection also dictate the features of underfloor heating cables. According to their structure and the number of wires, they are divided into single-core and double-core. Accordingly, there are some nuances in their connection schemes.
Connecting a two-core cable to the thermostat
Double-core heating cable has two current-carrying conductors under the protective jacket. This kind of cable is more convenient than the single-core construction, as it is connected to the thermostat only at one end. Let’s look at a typical wiring diagram:
We can see that there are three wires in one 2-wire cable, two of them are current-carrying (brown and blue), one is grounding (green-yellow). Pin 3 connects the brown wire (phase), pin 4 connects the blue wire (zero), and pin 5 connects the green wire (ground).
The thermostat, the diagram of which we have just reviewed, does not include a grounding terminal. In the presence of the grounding terminal installation is much easier.
Connecting a single wire cable
In a single-core cable has only one current-carrying conductor, usually it is white. The second wire. green. is the ground of the PE shield. The wiring diagram can be as follows:
The thermostat pins 3 and 4 are supplied with white wires (both ends of a single core cable), and pin 5 has a green ground wire.
About grounding and grounding for dummies
My bitter experience as an electrician allows me to assert: If your “grounding” is done properly. that is, you have a place to connect the “grounding” conductors, and all the plugs and sockets have a “grounding” contacts. I envy you, and you have nothing to worry about.
What is the problem why you can not connect the ground wire to the heating pipes or water supply??
Realistically in urban environments, stray currents, etc. The interfering factors are so great that anything can be on the radiator. However, the main problem is that the triggering current of the circuit breakers is quite large. Accordingly, one of the options for a possible accident. Short-circuiting phase to ground with a leakage current is just about the limit of automatic operation, that is, at best, 16 amps. So we divide 220v by 16A, we get 15 ohms. Just 30 meters of pipe, and you get 15 ohms. And the current flows somewhere in the direction of the unsawed woods. But it doesn’t matter. It is important that in the next apartment (to which 3 meters, not 30, voltage on the faucet is almost the same 220.), but on, say, a sewer pipe, it’s a real zero or so.
And now the question. what will happen to the neighbor, if he, sitting in the bathroom (connected to the sewer by opening a plug) touches the faucet? You guessed it?
The prize is. prison. Under the article on electrical safety violations resulting in casualties.
Don’t forget that you can’t imitate the “grounding” circuit. Connecting in euro socket “zero working” and “zero protective” wires, as it is sometimes practiced by some “craftsmen. This replacement is extremely dangerous. It is not uncommon for “operating zero” in a panel to be burned out. After that, on the casing of your refrigerator, computer, etc.д. is very firmly placed 220V. The consequences will be about the same as with the neighbor, with the difference that for this no one will be liable except for the one who made the connection. And as practice shows, this is done by the owners themselves.к. Consider themselves enough experts not to call the electrician.
One of the variants of “grounding” is grounding. But not as in the case described above. The fact that the body of the switchboard on your floor has a zero potential, but to be more precise, the zero conductor passing through this very switchboard, simply has a contact with the body of the switchboard through bolted connection. The neutral conductors of the apartments on this floor also connect to the housing of the switchboard. Let’s consider this point in detail. That we see, each of these ends of the brought to his bolt (in practice, however, often encountered on the pair connection of these ends). That’s just there and need to connect our newly formed conductor, which will later be called “grounding.
In this situation, too, has its own nuances. What prevents the “zero” from burning out at the entrance to the house. As a matter of fact, nothing. One can only hope that there are fewer houses in the city than apartments, and hence the percentage of this problem is much lower. But this again is the Russian “luck”, which does not solve the problem.
The only right solution, in this situation. Take a metal corner of 40×40 or 50×50, 3 meters long, to hammer it into the ground so that it does not stumble, namely, dig a hole at two bayonet deep and maximally hammered there our corner, and from it to wire PV-3 (flexible, multicore), cross section of at least 6 mm. kv. to, your switchboard.
Ideally, the “ground loop” should consist of 3. You need four angles that are welded together with a strip of metal of the same width. The distance between the angles must be 2 m.
Just do not drill a hole in the ground with a meter drill and lower the pin there. This is not right. And the efficiency of such grounding is close to zero.
But as in any method there are disadvantages. You are of course lucky if you live in a detached house, or at least on the first floor. And what about those who live on the floor at 7-8? Stock up on 30 meters of wire?
So how do we find a way out of this situation?? I’m afraid that even the most experienced electricians won’t give you the answer to this question.
For wiring in the house you need a copper ground wire, the appropriate length, and a cross section of not less than 1.5 mm. sq. And, of course, an outlet with a “grounding” contact. Box, baseboard, bracket. matter of aesthetics. The ideal is when you are doing renovations. In this case I recommend to choose a cable with three cores in double insulation, better VVG. One end of the wire gets under the free bolt of the switchboard busbar connected to the case of the switchboard, and the other end. to the “grounding” contact of the socket. If there is a RCD in the panel, the grounding conductor must not have contact with the N conductor anywhere on the mowing line (otherwise the RCD will trip).
Do not forget that the “ground” has no right to be broken by any switches.
How to wire underfloor heating & radiator zones. UFH WIRING GUIDE
Underfloor heating without grounding
When equipping space heating systems, many people opt for infrared underfloor heating. This is because they can be installed even under temperature-sensitive floor coverings. Due to the high efficiency, cost-effectiveness and speed of heating they are able to heat evenly all the available space, providing the most favorable air temperature.
But in order to take advantage of all these advantages, it is necessary to observe safety rules when installing them, especially in rooms with high humidity. All measures should be taken to ensure not only the quality of insulation of heating elements from the floor surface, but also between themselves, so that a high level of electrical safety is ensured in the event of abnormal situations.